IRF4 and Miyoshi myopathy: Whereas part of them are de novo expressed in MM as compared to normal B cell differentiation, that is, IRF1 and FOXP2, others show elevated levels in normal PCs and are further up-regulated in MM, that is, IRF4 and FOXO4, and a third group is down-regulated in normal PCs as compared to NBCs, GCBs, and MBCs but showed increased expression in MM (Fig. 2B).